Liquid crystal display and repairing method thereof

ABSTRACT

A liquid crystal display includes a plurality of data lines and a plurality of pixels arranged in a matrix, wherein the plurality of pixels include a first pixel and a second pixel, and each of the first pixel and the second pixel includes a first subpixel electrode and a second subpixel electrode, a first switching element, a second switching element, a third switching element, and a voltage-changing capacitor, wherein a first source electrode on the first switching element and a second source electrode on the second switching element from the first pixel are connected to a data line, the first source electrode and the second source electrode of the second pixel are disconnected from the plurality of data lines, and the two terminals of the voltage-changing capacitor of the second pixel are shorted to each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2009-0097443 filed in the Korean IntellectualProperty Office on Oct. 13, 2009, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a liquid crystal display and arepairing method thereof.

(b) Description of the Related Art

One of the most widely used flat panel displays, a liquid crystaldisplay (LCD) includes two display panels, each provided with fieldgenerating electrodes such as pixel electrodes and a common electrode,and a liquid crystal (LC) layer interposed there between. The LCDdisplays images by applying voltages to the field-generating electrodeson the display panel to generate an electric field across the LC layer.The electric field across the LC layer determines the orientation of LCmolecules therein to adjust the polarization of incident light.

The liquid crystal layer includes a liquid crystal material havingrefractive anisotropy. Because of the refractive anisotropy of theliquid crystal material however, large differences in the color and thecontrast ratio can occur between different viewing angles of the liquidcrystal display, such that side visibility may be inferior to frontvisibility, thereby narrowing the viewing angle of the liquid crystaldisplay. To solve this problem, a method has been proposed in which onepixel electrode is divided into two subpixel electrodes, and the twosubpixel electrodes are applied with different voltages. Each subpixelelectrode is connected to a thin film transistor as a three terminalelement for switching the applied voltage.

However, in the process for manufacturing the liquid crystal display,deterioration of the channel of the thin film transistor can occur whenimpurities are introduced, or when the light used to form aphotosensitive film for patterning a conductive layer is not suitablyfocused. Such deterioration can cause a subpixel electrode that is notto be applied with the data voltage, to be applied with the datavoltage, such that the display quality deteriorates.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

A liquid crystal display according to one aspect includes a plurality ofdata lines and a plurality of pixels arranged in a matrix, wherein theplurality of pixels include a first pixel and a second pixel, and eachof the first pixel and the second pixel includes a first subpixelelectrode and a second subpixel electrode, a first switching elementincluding a first drain electrode connected to the first subpixelelectrode and a first source electrode facing the first drain electrode,a second switching element including a second drain electrode connectedto the second subpixel electrode and a second source electrode facingthe second drain electrode, a third switching element including a thirdsource electrode connected to the second drain electrode and a thirddrain electrode facing the third source electrode, and avoltage-changing capacitor including the third drain electrode and acommon voltage line transmitting a common voltage as its two terminals,wherein the first source electrode and the second source electrode ofthe first pixel are connected to a data line of the plurality of datalines, the first source electrode and the second source electrode of thesecond pixel are disconnected from any of the plurality of data lines,and the two terminals of the voltage-changing capacitor of the secondpixel are shorted to each other.

The liquid crystal display further includes a plurality of first gatelines, wherein one first gate line is connected to the first switchingelement and the second switching element of the first pixel and onefirst gate line is connected to the first switching element and thesecond switching element of the second pixel, and a plurality of secondgate lines, wherein one second gate line is connected to the thirdswitching element of the first pixel and one second gate line isconnected to the third switching element of the second pixel.

The first subpixel electrode of the second pixel may be electricallyconnected to the first source electrode of the second pixel regardlessof, that is, independently of, a gate signal of the first gate line.

The second subpixel electrode of the second pixel may be electricallyconnected to the second source electrode of the second pixel regardlessof a gate signal of the first gate line.

The second gate line may be applied with a gate-off voltage Voff whenthe first gate line is applied with a gate-on voltage Von, and the firstgate line may be applied with the gate-off voltage Voff when the secondgate line is applied with the gate-on voltage Von.

In the first pixel, the voltages of the first subpixel electrode and thesecond subpixel electrode may be changed when the second gate line isapplied with the gate-on voltage Von.

In the second pixel, the common voltage may be transmitted to the secondsubpixel electrode when the second gate line is applied with the gate-onvoltage Von.

In the second subpixel, the first subpixel electrode may be electricallyconnected to the second subpixel electrode when the first gate line isapplied with the gate-on voltage Von.

In the second subpixel, the second subpixel electrode may be appliedwith the common voltage when the second gate line is applied with thegate-on voltage Von.

In the second pixel, the common voltage may be transmitted to the secondsubpixel electrode.

The common voltage may be also transmitted to the first subpixelelectrode in the second pixel.

A method for repairing a liquid crystal display according to one aspectis provided. The liquid crystal display including a plurality of datalines and a first pixel and a second pixel, wherein the first pixel andthe second pixel respectively include a first subpixel electrode and asecond subpixel electrode, a first switching element including a firstdrain electrode connected to the first subpixel electrode and a firstsource electrode facing the first drain electrode, a second switchingelement including a second drain electrode connected to the secondsubpixel electrode and a second source electrode facing the second drainelectrode, a third switching element including a third source electrodeconnected to the second drain electrode and a third drain electrodefacing the third source electrode, and a voltage-changing capacitorincluding the third drain electrode and a common voltage linetransmitting a common voltage as its two terminals, the method includingdisconnecting the first source electrode and the second source electrodeof the second pixel from any of the plurality of data lines, andshorting the two terminals of the voltage-changing capacitor in thesecond pixel.

The first source electrode and the second source electrode of the firstpixel may be connected to a data line of the plurality of data lines.

The liquid crystal display may further include a plurality of first gatelines, wherein one first gate line is connected to the first switchingelement and the second switching element of the first pixel and onefirst gate line is connected to the first switching element and thesecond switching element of the second pixel, and a plurality of secondgate lines, wherein one second gate line is connected to the thirdswitching element of the first pixel and one second gate line isconnected to the third switching element of the second.

The first subpixel electrode of the second pixel may be electricallyconnected to the first source electrode of the second pixel regardlessof a gate signal of the first gate line.

The second subpixel electrode of the second pixel may be electricallyconnected to the second source electrode of the second pixel regardlessof a gate signal of the first gate line.

The second gate line may be applied with the gate-off voltage Voff whenthe first gate line is applied with the gate-on voltage Von, and thefirst gate line may be applied with the gate-off voltage Voff when thesecond gate line is applied with the gate-on voltage Von.

In the first pixel, the voltages of the first subpixel electrode and thesecond subpixel electrode may be changed when the second gate line isapplied with the gate-on voltage Von.

In the second pixel, the common voltage may be transmitted to the secondsubpixel electrode when the second gate line is applied with the gate-onvoltage Von.

In the second pixel, the first subpixel electrode may be electricallyconnected to the second subpixel electrode when the first gate line isapplied with the gate-on voltage Von.

In the second pixel, the first subpixel electrode may also be appliedwith the common voltage when the second gate line is also applied withthe gate-on voltage Von.

In the second pixel, the common voltage may be transmitted to the secondsubpixel electrode.

The common voltage may also be transmitted to the first subpixelelectrode in the second pixel.

At least one of the disconnecting of the first source electrode and thesecond source electrode of the second pixel from any of the plurality ofdata lines and the shorting of the two terminals of the voltage-changingcapacitor in the second pixel may comprise using a laser.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a liquid crystal display according to anexemplary embodiment,

FIG. 2 is an equivalent circuit diagram of two subpixels and a structureof a liquid crystal display according to an exemplary embodiment,

FIG. 3 is an equivalent circuit diagram of one pixel of a liquid crystaldisplay according to an exemplary embodiment,

FIG. 4 is illustrates a gate signal of a liquid crystal displayaccording to an exemplary embodiment,

FIG. 5 is a layout view of a liquid crystal display according to anexemplary embodiment,

FIG. 6 is an enlarged view of a portion of the liquid crystal displayshown in FIG. 5,

FIG. 7 is a cross-sectional view of the liquid crystal display shown inFIG. 5 and FIG. 6 taken along the line VII-VII,

FIG. 8 is a layout view of a repaired pixel of a liquid crystal displayaccording to an exemplary embodiment,

FIG. 9 is a cross-sectional view of the liquid crystal display shown inFIG. 8 taken along the line IX-IX,

FIG. 10 is an equivalent circuit diagram of a repaired pixel of theliquid crystal display according to an exemplary embodiment,

FIG. 11 is a view showing two subpixel electrodes and a display area ofa liquid crystal display according to an exemplary embodiment,

FIG. 12 is a layout view of a liquid crystal display according to anexemplary embodiment, and

FIG. 13 is a cross-sectional view of the liquid crystal display shown inFIG. 12 taken along the line XIII-XIII.

DESCRIPTION OF REFERENCE NUMERALS INDICATING PRIMARY ELEMENTS IN THEDRAWINGS

3: liquid crystal layer 71: cutout 100: lower panel 110, 210: substrate121: first gate line 123: second gate line 124l, 124h, 124c: gateelectrode 125: common voltage line 140: gate insulating layer 151, 154,154h, 154l, 154c: semiconductor 161, 163l, 165l, 163h, 165h: ohmiccontact 171: data line 173h, 173l, 173c: source electrode 175h, 175l,175c: drain electrode 180, 180p, 180q: passivation layer 185, 185h,185l: contact hole 191, 191h, 191l: pixel electrode 200: upper panel220: light blocking member 230: color filter 250: overcoat 270: commonelectrode

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments will be described more fully hereinafter with referenceto the accompanying drawings. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc.,may be exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as, for example, a layer, film, region, or substrate isreferred to as being “on” another element, it can be directly on theother element, or intervening elements may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Now, a liquid crystal display according to an exemplary embodiment willbe described with reference to FIG. 1 and FIG. 2.

FIG. 1 is a block diagram of a liquid crystal display according to anexemplary embodiment, and FIG. 2 is an equivalent circuit diagram of twosubpixels and a structure of a liquid crystal display according to anexemplary embodiment.

Referring to FIG. 1, a liquid crystal display according to an exemplaryembodiment includes a liquid crystal panel assembly 300, a gate driver400, and a data driver 500.

In an equivalent circuit of the liquid crystal panel assembly 300, theliquid crystal panel assembly 300 includes a plurality of signal linesG1-Gn and D1-Dm, and a plurality of pixels PX arranged in an approximatematrix. In the structure shown in FIG. 2, the liquid crystal panelassembly 300 includes a lower panel 100 and an upper panel 200 that arefacing each other, and a liquid crystal layer 3 interposed therebetween.

The signal lines G1-Gn and D1-Dm that are provided in the lower panel100 include a plurality of gate lines G1 to Gn for transmitting gatesignals (referred to as “scanning signals”) and a plurality of datalines D1 to Dm for transmitting a data voltage.

Each pixel PX, for example the pixel PX connected to the i-th (i=1, 2, .. . , n) gate line Gi and the j-th (j=1, 2, . . . , m) data line Dj,includes a first subpixel and a second subpixel. The first and secondsubpixels respectively include first and second liquid crystalcapacitors Clch and Clcl. The first and second subpixels further includea switching element (not shown) connected to the gate lines G1-Gn, thedata lines D1-Dm, and the first and second liquid crystal capacitorsClch and Clcl.

The first and second liquid crystal capacitor Clch and Clcl include afirst and second subpixel electrode 191 h and 191 l, respectively, onthe lower panel 100 and a common electrode 270 on the upper panel 200 astwo terminals. The liquid crystal layer 3 between the two terminalsserves as a dielectric material. The first and second subpixelelectrodes 191 h and 191 l are separated from each other and form onepixel electrode 191. The common electrode 270 is formed on the wholesurface of the upper panel 200 and is applied with the common voltageVcom. The liquid crystal layer 3 has negative dielectric anisotropy, andliquid crystal molecules of the liquid crystal layer 3 may be alignedsuch that their major axes are perpendicular to the surfaces of the twodisplay panels when an electric field is not applied. In an alternativeto the structure illustrated in FIG. 2, the common electrode 270 may beformed on the lower panel 100.

For the color display, each pixel PX uniquely displays one of threeprimary colors (spatial division) or each pixel PX alternately displaysthe three primary colors (temporal division) as time passes, and adesired color is recognized by a spatial or temporal sum of the primarycolors. For example, the primary colors may be three primary colors ofred, green, and blue. FIG. 2 shows a color filter 230 displaying one ofthe primary colors on a region of the upper panel 200 for each of thepixels as an example of spatial division. In an alternative to the caseillustrated in FIG. 2, the color filter 230 may be provided on or underthe subpixel electrodes 191 h and 191 l of the lower panel 100.

Polarizers (not shown) may be provided on the outer surface of thedisplay panels 100 and 200, and the polarization axes of the twopolarizers may be crossed.

Referring again to FIG. 1, the data driver 500 is connected to the datalines D1-Dm of the liquid crystal panel assembly 300, and applies thedata voltage to the data lines D1-Dm.

The gate driver 400 is connected to the gate lines G1 to Gn of theliquid crystal panel assembly 300, and applies gate signals obtained bycombining a gate-on voltage

Von for turning on a switching element and a gate-off voltage Voff forturning off the switching element to the gate lines G1 to Gn.

Next, one example of the liquid crystal display will be described withreference to FIG. 3 as well as FIG. 1 and FIG. 2.

FIG. 3 is an equivalent circuit diagram of one pixel of a liquid crystaldisplay according to an exemplary embodiment.

Referring to FIG. 3, a liquid crystal display according to an exemplaryembodiment has signal lines that include a first gate line 121, a secondgate line 123, a common voltage line 125, and a data line 171, and aplurality of pixels PX connected thereto.

The pixel PX includes a first switching element Qh, a second switchingelement Ql, a third switching element Qc, a first liquid crystalcapacitor Clch, a second liquid crystal capacitor Clcl, and avoltage-changing capacitor Cstd.

The first and second thin film transistors Qh and Ql are three terminalelements provided in the lower panel 100 and have a control terminalconnected to the gate line 121, an input terminal connected to the dataline 171, and an output terminal connected to the first and secondliquid crystal capacitors Clch and Clcl, respectively.

The third thin film transistor Qc is a three terminal element providedin the lower panel 100 and has a control terminal connected to thesecond gate line 123, an input terminal connected to the second liquidcrystal capacitor Clcl, and an output terminal connected to thevoltage-changing capacitor Cstd.

The voltage-changing capacitor Cstd is connected to the output terminalof the third switching element Qc and the common voltage line 125. Thecommon voltage line 125 provided in the lower panel 100 and the outputterminal of the third switching element Qc overlap via an insulator.

The first liquid crystal capacitor Clch and the second liquid crystalcapacitor Clcl are described above such that redundant description isomitted.

An operation of a liquid crystal display according to an exemplaryembodiment will be described with reference to FIG. 4 as well as FIG. 1to FIG. 3.

FIG. 4 is a view showing a gate signal Vgn of the first gate line 121and a gate signal Vgc of the second gate line 123 in the liquid crystaldisplay shown in FIG. 3.

If the first gate line 121 is applied with a gate-on voltage Von, thefirst switching element Qh and the second switching element Ql connectedthereto are turned on.

Accordingly, the data voltage of the data line 171 is simultaneouslyapplied to both the first and second subpixel electrodes 191 h and 191 lthrough the turned-on first and second switching elements Qh and Ql. Thefirst and second liquid crystal capacitors Clch and Clcl are charged bya difference between the common voltage Vcom of the common electrode 270and the voltage of the first and second subpixel electrodes 191 h and191 l, such that the charging voltage of the first liquid crystalcapacitor Clch is the same as the charging voltage of the second liquidcrystal capacitor Clcl. In this case, the second gate line 123 isapplied with the gate-off voltage Voff.

Next, if the first gate line 121 is applied with the gate-off voltageVoff, and simultaneously the second gate line 123 is applied with thegate-on voltage Von, the first and second switching elements Qh and Qlconnected to the gate line 121 are turned off, and the third switchingelement Qc is turned on. Accordingly, the charges of the second subpixelelectrode 191 l connected to the output terminal of the second switchingelement Ql flow into the voltage-changing capacitor Cstd such that thevoltage of the second liquid crystal capacitor Clcl is decreased.

In an example of the case in which the liquid crystal display accordingto the present exemplary embodiment is driven by frame inversion, whenthe data line 171 has the positive data voltage with respect to thecommon voltage Vcom in the present frame, negative charges are gatheredin the voltage-changing capacitor Cstd after the previous frame isfinished. Accordingly, in the present frame, if the third switchingelement Qc is turned on, the positive charges of the second subpixelelectrode 191 l flow into the voltage-changing capacitor Cstd throughthe third switching element Qc, and the negative charges of thevoltage-changing capacitor Cstd flow into the second subpixel electrode191 l such that the voltage of the second subpixel electrode 191 isdecreased. Next, in the immediately following frame, if the thirdswitching element Qc is turned on in the state in which the negativecharges are charged in the second subpixel electrode 191 l, the negativecharges of the second subpixel electrode 191 l flow into thevoltage-changing capacitor Cstd such that the negative charges aregathered in the voltage-changing capacitor Cstd, and the voltage of thesecond liquid crystal capacitor Clcl is decreased.

Accordingly, the charging voltages of the first and second liquidcrystal capacitors Clch and Clcl are different such that the lateralvisibility of the liquid crystal display may be improved.

A liquid crystal display according to an exemplary embodiment of thepresent invention and a manufacturing method thereof will be describedwith reference to FIG. 5 to FIG. 7.

FIG. 5 is a layout view of a liquid crystal display according to anexemplary embodiment, FIG. 6 is an enlarged view of a portion of theliquid crystal display shown in FIG. 5, and FIG. 7 is a cross-sectionalview of the liquid crystal display shown in FIG. 5 and FIG. 6 takenalong the line VII-VII.

The liquid crystal display according to the present exemplary embodimentincludes the lower panel 100 and the upper panel 200 which are facingeach other, and a liquid crystal layer 3 interposed between two displaypanels 100 and 200. Polarizers (not shown) may be provided at the outersurface of the display panels 100 and 200.

The lower panel 100 will now be described.

A plurality of gate conductors including a plurality of first gate lines121, a plurality of second gate lines 123, and a common voltage line 125are formed on an insulation substrate 110.

The first gate line 121 and the second gate line 123 extend in asubstantially transverse direction and each transmits a gate signal. Thefirst gate line 121 includes a first gate electrode 124 h and a secondgate electrode 124 l that protrude upward, and the second gate line 123includes a third gate electrode 124 c that protrudes upward. The firstgate electrode 124 h and the second gate electrode 124 l are connectedto each other, thereby forming one protrusion.

The common voltage line 125 is mainly extended in the transversedirection, and transfers a predetermined voltage such as a commonvoltage Vcom. The common voltage line 125 includes left and right commonvoltage electrodes 128 b that protrude downward, and an expansion 126 bconnected to the ends of the right common voltage electrode 128 b.

A gate insulating layer 140 is formed on the gate conductors 121, 123,and 125.

A plurality of semiconductor stripes 151 made of amorphous silicon(a-Si), polysilicon, or the like are formed on the gate insulating layer140. The semiconductor stripes 151 are mainly extended in thelongitudinal direction.

Each semiconductor stripe 151 includes first and second semiconductors154 h and 154 l that extend toward the first and second gate electrodes124 h and 124 l and which are connected to each other, and a thirdsemiconductor 154 c connected to the second semiconductor 154 l.

A plurality of ohmic contact stripes 161 are formed on the semiconductorstripes 151, a pair of ohmic contacts 163 h and 165 h are formed on thefirst semiconductor 154 h, and a pair of ohmic contacts 163 l and 165 lare formed on the second semiconductor 154 l. A pair of ohmic contacts(not shown) are also formed on the third semiconductor 154 c. The ohmiccontacts 163 l and 163 h are connected to the ohmic contact stripes 161.

A data conductor including a plurality of data lines 171, a plurality offirst drain electrodes 175 h, a plurality of second drain electrodes 175l, a plurality of third source electrodes 173 c, and a plurality ofthird drain electrodes 175 c is formed on the ohmic contacts 161, 165 h,and 165 l.

The data lines 171 transmit data signals and extend in the longitudinaldirection thereby intersecting the first gate lines 121 and the secondgate lines 123. Each data line 171 includes a first source electrode 173h and a second source electrode 173 l extending, respectively, towardthe first gate electrode 124 h and the second gate electrode 124 l. Thefirst source electrode 173 h and the second source electrode 173 l areconnected to each other.

The first drain electrode 175 h, the second drain electrode 175 l, andthe third drain electrode 175 c each have one end portion that has awide area and the other end portion that has a linear, or bar shape. Thebar-shaped end portions of the first drain electrode 175 h and thesecond drain electrode 175 l are partially enclosed by the first sourceelectrode 173 h and the second source electrode 173 l, respectively. Thebar-shaped end portion of the third source electrode 173 c is partiallyenclosed by the third source electrode 173 c. The wide end of the seconddrain electrode 175 l is connected to the third source electrode 173 c.The wide end 177 c of the third drain electrode 175 c overlaps theexpansion 126 b of the common voltage line 125, thereby forming thevoltage-changing capacitor Cstd.

The first, second, and third gate electrodes 124 h, 124 l, and 124 c,the first, second, and third source electrodes 173 h, 173 l, and 173 c,and the first, second, and third drain electrodes 175 h, 175 l, and 175c form, respectively, the first, second, and third thin film transistors(TFT) Qh, Ql, and Qc along with the first, second, and thirdsemiconductor islands 154 h, 154 l, and 154 c. A channel of the thinfilm transistors is respectively formed in the semiconductor 154 h, 154l, and 154 c between the source electrodes 173 h, 173 l, and 173 c andthe drain electrodes 175 h, 175 l, and 175 c.

Also, the semiconductor stripes 151 including the semiconductors 154 h,154 l, and 154 c, with the exception of the channel region between thesource electrodes 173 h, 173 l, and 173 c, and the drain electrodes 175h, 175 l, and 175 c, have substantially the same shape as the dataconductors 171, 175 h, 175 l, and 175 c, and the underlying ohmiccontacts 161 and 165 h. That is, the semiconductor stripes 151 includingthe semiconductors 154 h, 154 l, and 154 c have a portion that isexposed without being covered by the data conductors 171, 175 h, 175 l,and 175 c, and a portion between the source electrodes 173 h, 173 l, and173 c and the drain electrodes 175 h, 175 l, and 175 c.

A passivation layer 180 is formed on the data conductors 171, 175 h, 175l and 175 c and the exposed semiconductors 154 h, 154 l, and 154 c.

The passivation layer 180 has a plurality of contact holes 185 h and 185l respectively exposing the wide end of the first drain electrode 175 hand the wide end of the second drain electrode 175 l.

A pixel electrode 191 is formed on the passivation layer 180.

The overall shape of pixel electrode 191 is substantially rectangular.Pixel electrode 191 includes the first and second subpixel electrodes191 h and 191 l that are engaged with each other and have a gap 91 therebetween. The first subpixel electrode 191 h is formed in the centralportion of the second subpixel electrode 191 l, and the gap 91 includesone longitudinal portion and a pair of oblique portions respectivelydisposed upward and downward with respect to an imaginary transversecentral line (or the common voltage line 125).

The second subpixel electrode 191 l includes a central electrode 191 la,upper and lower electrodes 191 lb, and a protrusion 192 l that protrudesdownward from the lower electrode 191 lb. The central electrode 191 laincludes a cutout 93 that has a substantially triangular shape, and isformed in the central portion of the left edge of the central electrode.The upper and the lower electrodes 191 b each include a cutout 92.

The edges of the oblique portion of the gap 91, and the cutouts 92 and93, are inclined with respect to the first and second gate lines 121 and123 and the common voltage line 125 by an angle of about 45°.

The number of cutouts may vary depending on design factors, such as thelength ratio of the horizontal side and the vertical side of the pixelelectrode 191, the type of liquid crystal layer 3, or othercharacteristics.

The area of the second subpixel electrode 191 l may be in the range of1.0 to 2.2 times the area of the first subpixel electrode 191 h.

The first subpixel electrode 191 h receives the data voltage from thefirst drain electrode 175 h through the contact hole 185 h, and thesecond subpixel electrode 191 l receives the data voltage from thesecond drain electrode 175 l through the protrusion 192 l and thecontact hole 185 l.

An alignment layer 11 is formed on the first and second subpixelelectrodes 191 h and 191 l and the passivation layer 180. The alignmentlayer 11 may be a vertical alignment layer.

Next, the upper panel 200 will be described.

A light blocking member 220 referred to as a black matrix and aplurality of color filters 230 are formed on an insulation substrate210, and an overcoat 250 is formed on the light blocking member 220 andthe color filters 230.

A common electrode 270 made of a transverse conductor or metal such asITO or IZO is formed on the overcoat 250. The common electrode 270 has aplurality of cutouts 71 formed substantially parallel to the obliqueportions of the cutouts 92 of the pixel electrode 191.

An alignment layer 21 may be formed on the common electrode 270. Thealignment layer 21 may be a vertical alignment layer.

The liquid crystal layer 3 between the lower panel 100 and the upperpanel 200 includes liquid crystal molecules having dielectricanisotropy, and may be oriented such that the major axes of the liquidcrystal molecules of the liquid crystal layer 3 are almost perpendicularto the surfaces of the two display panels 100 and 200 when no electricfield is applied.

The first and second subpixel electrodes 191 h and 191 l applied withthe data voltage form the electric field along with the common electrode270 of the upper panel 200 such that the electric field determines thedirection of the liquid crystal molecules in the liquid crystal layer 3between two electrodes 191 and 270. The degree of change of thepolarization of the light that is incident to the liquid crystal layer 3depends upon the inclination degree of the liquid crystal molecules, andthis change of the polarization appears as a change of transmittance bythe polarizer, thereby displaying images of the liquid crystal display.

The first subpixel electrode 191 h and the common electrode 270 form thefirst liquid crystal capacitor Clch along with the liquid crystal layer3 interposed there between, and the second subpixel electrode 191 l andthe common electrode 270 form the second liquid crystal capacitor Clclalong with the liquid crystal layer 3 interposed there between, therebymaintaining the voltage of the subpixel electrodes after the first andsecond thin film transistors Qh and Ql are turned off.

After the first and the second thin film transistors Qh and Ql areturned off, the third thin film transistor Qc is turned on such that thesecond liquid crystal capacitor Clcl is connected to thevoltage-changing capacitor Cstd, and thereby the voltage of the secondliquid crystal capacitor Clcl is decreased. If the voltages of the firstand second liquid crystal capacitors Clch and Clcl are different, theluminances of the display at the first subpixel 191 h and the secondsubpixel electrode 191 l are also different, and accordingly, thevoltages of the first and second liquid crystal capacitors Clca and Clcbare appropriately controlled, thereby improving the lateral visibility.Various characteristics and operations of the liquid crystal displayaccording to the exemplary embodiments shown in FIG. 1 to FIG. 4 mayalso be applied to the present exemplary embodiment.

Next, a manufacturing method of a lower panel 100 of the liquid crystaldisplay shown in FIG. 5 to FIG. 7 will be described.

First, a gate conductive layer (not shown) is deposited on an insulationsubstrate 110 made of transparent glass, and a photosensitive film iscoated thereon. The photosensitive film is irradiated by light through amask (not shown) and is developed to form a photosensitive film pattern(not shown), and the gate conductive layer is etched by using thephotosensitive film pattern as an etching mask to form a plurality ofgate conductors including a plurality of first gate lines 121, aplurality of second gate lines 123, and a common voltage line 125.

Next, a gate insulating layer 140 made of an inorganic insulator or anorganic insulator is deposited on the gate conductor.

Next, a semiconductor layer (not shown) and a semiconductor layer (notshown) that is doped with an impurity are sequentially deposited bychemical vapor deposition on the gate insulating layer 140, a dataconductive layer (not shown) is formed by sputtering, and aphotosensitive film is coated thereon. Next, the photosensitive film isirradiated by light using a light exposer through a mask (not shown),and is developed to form a photosensitive film pattern (not shown) whichhas different thicknesses in different positions. Next, the dataconductive layer, the semiconductor layer doped with an impurity, andthe semiconductor layer are etched by using the photosensitive filmpattern as the etching mask to form a data conductor layer (not shown),an ohmic contact layer (not shown), and a plurality of semiconductorstripes 151 having the same plane shape.

Next, a portion of the photosensitive film pattern is removed, and theexposed data conductor layer and ohmic contact layer are etched to form(i) the channel regions of the first, second, and third thin filmtransistors Qh, Ql, and Qc, and (ii) a data conductor that includes aplurality of data lines 171, a plurality of first drain electrodes 175h, a plurality of second drain electrodes 175 l, a plurality of thirdsource electrodes 173 c, and a plurality of third drain electrodes 175c, and a plurality of ohmic contacts 161, 165 h, and 165 l.

Next, a passivation layer 180 is formed on the data conductor andpatterned to form a plurality of contact holes 185 h and 185 l, and atransparent conductive layer of IZO or ITO is formed on the passivationlayer 180 by sputtering, and then patterned to form a plurality of pixelelectrodes 191 including a gap 91 and cutouts 92 and 93.

In the manufacturing process of the liquid crystal display, forming thefirst, second, and third gate electrodes 124 h, 124 l, and 124 c, thefirst, second, and third semiconductors 154 h, 154 l, and 154 c, thefirst, second, and third source electrodes 173 h, 173 l, and 173 c, andthe first, second, and third drain electrodes 175 h, 175 l, and 175 c,which form the first, second, and third thin film transistors Qh, Ql,and Qc requires exposing the liquid crystal display to light. As theresult of various causes in the manufacturing of the liquid crystaldisplay, for instance if the light used is not appropriately focused oris misaligned, or if external foreign particles are introduced into thedisplay device, defects can occur in the channel regions of the first,second, and third thin film transistors Qh, Ql, and Qc. As a result ofsuch defects, the first, second, and third thin film transistors Qh, Ql,and Qc may always be turned on, regardless of the state of the gatesignal. Particularly, if the first and second thin film transistors Qhand Ql that are connected to the first and second subpixel electrodes191 h and 191 l and applied with the data voltage are defective, thefirst and second subpixel electrodes 191 h and 191 l may be applied withthe data voltage for the different pixels PX such that the image of thecorresponding pixel PX may not be displayed. Accordingly, thedeteriorated pixel PX is repaired to always display black. Particularly,referring to FIG. 5 to FIG. 7, the first thin film transistor Qh and thesecond thin film transistor Ql are close to each other such that theymay be simultaneously defective.

Next, a method for repairing a defective pixel that may occur in theliquid crystal display shown in FIG. 5 to FIG. 7, and the resultingrepaired liquid crystal display will be described with reference to FIG.8 to FIG. 11. In FIG. 8 to FIG. 11, the same constituent elements asdescribed in the previous exemplary embodiment are indicated by the samereference numerals. Certain redundant description is therefore omitted.

FIG. 8 is a layout view of a repaired pixel of a liquid crystal displayaccording to an exemplary embodiment, FIG. 9 is a cross-sectional viewof the liquid crystal display shown in FIG. 8 taken along the lineIX-IX, FIG. 10 is an equivalent circuit diagram of a repaired pixel ofthe liquid crystal display according to an exemplary embodiment, andFIG. 11 is a view showing two subpixel electrodes and a display area ofa liquid crystal display according to an exemplary embodiment.

Referring to FIG. 8 to FIG. 10, when the first thin film transistor Qhof the pixel of the liquid crystal display according to an exemplaryembodiment is defective, or the first and second thin film transistorsQh and Ql are defective, the portion A between the first sourceelectrode 173 h of the first thin film transistor Qh and the data line171 is disconnected by, for example, using a laser, and the wide end 177c of the third drain electrode 175 c and the expansion 126 b of thecommon voltage line 125 forming two terminals of the voltage-changingcapacitor Cstd are shorted (portion B) by using, for example, a laser.

Thus, the first and second thin film transistors Qh and Ql are separatedfrom the data line 171 such that they do not receive the data voltage,and the function of the voltage-changing capacitor Cstd is lost. Thethird drain electrode 175 c of the third thin film transistor Qc isdirectly connected to the common voltage Vcom. Accordingly, if thegate-on voltage Von is applied to the second gate line 123, therebyturning on the third thin film transistor Qc, the common voltage Vcom isapplied to the second subpixel electrode 191 l through the contact hole185 l such that the voltage applied to the second liquid crystalcapacitor Clcl is substantially 0. As a result, therefore, the firstdisplay area A1 corresponding to the second subpixel electrode 191 l ofFIG. 11 displays black. In FIG. 11, the first display area Al is animage display area corresponding to the second subpixel electrode 191 l,and the second display area A2 is the image display area correspondingto the first subpixel electrode 191 h.

On the other hand, when the channel region of the third thin filmtransistor Qc is defective, the second subpixel electrode 191 l isapplied with the common voltage Vcom regardless of the gate signal Vgcof the second gate line 123 such that the first display area A1 of FIG.11 may display black.

Next, if the gate-on voltage Von is applied to the first gate line 121,the first and the second thin film transistors Qh and Ql are turned onsuch that the first subpixel electrode 191 h is connected to the secondsubpixel electrode 191 l through the turned-on first and second thinfilm transistors Qh and Ql and the contact hole 185 l. Accordingly, thevoltage of the first subpixel electrode 191 h is moved to the side ofthe common voltage Vcom, and the voltage of the first subpixel electrode191 h converges to the common voltage Vcom as the frame is repeated.Accordingly, the voltage applied to the first liquid crystal capacitorClch is substantially 0 such that the second display area A2corresponding to the first subpixel electrode 191 h of FIG. 11 displaysblack.

When the channel regions of the first and second thin film transistorsQh and Ql are defective, the first and second thin film transistors Qhand Ql may always be turned on, regardless of the gate signal Vgn of thefirst gate line 121, such that the common voltage Vcom is simultaneouslyapplied the first subpixel electrode 191 h when the common voltage Vcomis applied to the second subpixel electrode 191 l in this case.

When the third thin film transistor Qc is defective as well as the firstand second thin film transistors Qh and Ql, the common voltage Vcom maybe applied to both the first subpixel electrode 191 h and the secondsubpixel electrode 191 l regardless of the gate signal Vgn of the firstgate line 121 and the gate signal Vgc of the second gate line 123.

As described above, when the pixel of the liquid crystal display isdefective, for instance when defects in the first thin film transistorQh or the first and second thin film transistors Qh and Ql exist, thepixel defect that causes an abnormally bright light is turned off sothat the pixel displays black. This change is accomplished by easilyrepairing the corresponding pixel through the above-described method,and thereby display deterioration may be prevented.

In the above-described exemplary embodiment, the pixel defects due to adefect of the channel region of the first thin film transistor Qh andthe second thin film transistor Ql is described. However the embodimentis not limited thereto, and the method of repairing the liquid crystaldisplay according to the exemplary embodiments may be applied to variouscases in which the second display area A2 corresponding to the firstsubpixel electrode 191 h, or the first display area A1 corresponding tothe second subpixel electrode 191 l, does not execute the normal displayoperation.

Next, a method of repairing a liquid crystal display and a repairedpixel of a liquid crystal display according to another exemplaryembodiment will be described with reference to FIG. 12 and FIG. 13. Thesame constituent elements described in the previous exemplary embodimentare indicated by the same reference numerals. Certain redundantdescription is therefore omitted.

FIG. 12 is a layout view of a liquid crystal display according to anexemplary embodiment, and FIG. 13 is a cross-sectional view of theliquid crystal display shown in FIG. 12 taken along the line XIII-XIII.

A liquid crystal display according to the present exemplary embodimentincludes a lower panel 100 and an upper panel 200 that are facing eachother, and a liquid crystal layer 3 interposed between the two displaypanels 100 and 200.

First, referring to the upper panel 200, a common electrode 270 isformed on an insulation substrate 210, and an alignment layer (notshown) is formed on the common electrode 270.

The liquid crystal layer 3 between the lower panel 100 and the upperpanel 200 has negative dielectric anisotropy, and may be oriented suchthat the major axes of the liquid crystal molecules of the liquidcrystal layer 3 are almost perpendicular to the surfaces of the twodisplay panels 100 and 200 when no electric field is applied.

Next, referring to the lower panel 100, a plurality of gate conductorsincluding a plurality of first gate lines 121, a plurality of secondgate lines 123, and a common voltage line 125 are formed on aninsulation substrate 110. The common voltage line 125 includes anelectrode 129 that protrudes upward and downward, a pair of longitudinalportions 128 that extend vertically to the first gate line 121, and atransverse portion 127 connecting the ends of a pair of longitudinalportions 128 to each other. The transverse portion 127 includes anexpansion 126 expanding downward and a protrusion 122 that protrudesdownward.

A gate insulating layer 140 is formed on the gate conductor 121, 123,and 125.

A plurality of semiconductor stripes 151 are formed on the gateinsulating layer 140. The semiconductor stripe 151 includes first andsecond semiconductors 154 h and 154 l that are connected to each other,and a third semiconductor 154 c connected to the second semiconductor154 l.

A plurality of ohmic contact stripes 161 are formed on the semiconductorstripe 151, a pair of ohmic contacts 163 h and 165 h are formed on thefirst semiconductor 154 h, and a pair of ohmic contacts (not shown) arerespectively formed on the second semiconductor 154 l and the thirdsemiconductor 154 c.

A data conductor that includes a plurality of data lines 171, aplurality of first drain electrodes 175 h, a plurality of second drainelectrodes 175 l, and a plurality of third drain electrodes 175 c isformed on the ohmic contacts 161 and 165 h. Data line 171 includes afirst source electrode 173 h and a second source electrode 173 l. Thefirst drain electrode 175 h, the second drain electrode 175 l, and thethird drain electrode 175 c each have one end portion that has a widearea and the other end portion that has a linear, bar shape. Thebar-shaped end portions of the first drain electrode 175 h and thesecond drain electrode 175 l are partially enclosed by the first sourceelectrode 173 h and the second source electrode 173 l, respectively. Thewide end of the second drain electrode 175 l is again extended, therebyforming the third source electrode 173 c that is curved and has a “U”shape. The wide end 177 c of the third drain electrode 175 c overlapswith the expansion 126 of the common voltage line 125 thereby formingthe voltage-changing capacitor Cstd, and the bar-shaped end thereof ispartially enclosed by the third source electrode 173 c.

The first, second, and third gate electrode 124 h, 124 l, and 124 c, thefirst, second, and third source electrode 173 h, 173 l, and 173 c, andthe first, second, and third drain electrode 175 h, 175 l, and 175 cform the first, second, and third thin film transistor Qh, Ql, and Qcalong with the first, second, and third semiconductor island 154 h, 154l, and 154 c.

A lower passivation layer 180 p typically made of an inorganic insulatorsuch as silicon nitride or silicon oxide is formed on the dataconductors 171, 175 h, 175 l, and 175 c and the exposed semiconductors154 h, 154 l, and 154 c, and a color filter 230 is formed on the lowerpassivation layer 180 p.

A light blocking member 220 is formed on the region that the colorfilter 230 does not occupy and on a portion of the color filter 230. Thelight blocking member 220 includes a portion that covers the regionwhere the first thin film transistor Qh, the second thin film transistorQl, and the third thin film transistor Qc, and also a portion thatextends along the data line 171. The light blocking member 220 includesan opening 225 exposing a substantial part of the first subpixelelectrode 191 h and the second subpixel electrode 191 l. The lightblocking member 220 may include an opening 227 disposed on the firstthin film transistor Qh and the second thin film transistor Ql, anopening 226 h disposed on the wide end of the first drain electrode 175h, an opening 226 l disposed on the wide end of the second drainelectrode 175 l, and an opening 228 disposed on the third thin filmtransistor Qc. The openings 226 h, 226 l, 227, and 228 where the lightblocking member 220 is removed are capable of being used to test fordefects in the thin film transistor etc. in the manufacturing process ofthe liquid crystal display.

An upper passivation layer 180 q is formed on the color filter 230 andthe light blocking member 220.

The lower passivation layer 180 p and the upper passivation layer 180 qhave a plurality of contact holes 185 h and 185 l respectively exposingthe wide ends of the first drain electrode 175 h and the second drainelectrode 175 l. The contact holes 185 h and 185 l are disposed in theopenings 226 h and 226 l of the light blocking member 220.

A pixel electrode including the first subpixel electrode 191 h and thesecond subpixel electrode 191 l is formed on the upper passivation layer180 q.

The overall shape of the first subpixel electrode 191 h is a quadrangle,and includes a cross stem 195 h that has a transverse stem and alongitudinal stem, an outer stem 196 h that encloses the periphery, anda protrusion 192 h that protrudes downward from the longitudinal stem ofthe cross stem 195 h.

The overall shape of the second subpixel electrode 191 l is also aquadrangle, and includes a cross stem 195 l that has a transverse stemand a longitudinal stem, an upper transverse portion 196 la, a lowertransverse portion 196 lb, and a protrusion 192 l that protrudes upwardfrom the upper portion of the longitudinal stem of the cross stem 195 land right and left longitudinal portions 193 la and 193 lb disposed onthe right and left sides of the first subpixel electrode 191 h. Theright and left longitudinal portions 193 la and 193 lb may preventcapacitive coupling between the data line 171 and the first subpixelelectrode 191 h.

The first subpixel electrode 191 h and the second subpixel electrode 191l are respectively divided into four subregions by the cross stems 195 hand 195 l. Each sub region includes a plurality of tiny branchelectrodes 199 h and 199 l obliquely extending outside from the crossstems 195 h and 195 l, and tiny slits 91 h and 91 l are disposed betweenthe neighboring tiny branches 199 h and 199 l.

The protrusion 192 h of the first subpixel electrode 191 h receives thedata voltage from the first drain electrode 175 h through the firstcontact hole 185 h, and the protrusion 192 l of the second subpixelelectrode 191 l receives the data voltage from the second drainelectrode 175 l through the second contact hole 185 l. Here, the datavoltage applied to the second subpixel electrode 191 l may be less thanthe data voltage applied to the first subpixel electrode 191 h.

An alignment layer (not shown) may be formed on the first and secondsubpixel electrodes 191 h and 191 l, and the upper passivation layer 180q.

In an exemplary embodiment, the first and second subpixel electrodes 191h and 191 l include four subregions where the length directions of thetiny branches 199 h and 199 l or the tiny slits 91 h and 91 l aredifferent such that the inclined directions of the liquid crystalmolecules of the liquid crystal layer 3 are all four directions.Therefore, the viewing angle of the liquid crystal display is widened byvarying the inclined directions of the liquid crystal molecules.

Also, the several characteristics and the operations of the liquidcrystal display according to the exemplary embodiment shown in FIG. 1 toFIG. 4 may be applied to the present exemplary embodiment.

When the pixel is defective in an exemplary embodiment as shown in FIG.12 and FIG. 13, the portion A is disconnected between the data line 171and the first source electrode 173 h of the first thin film transistorQh by using, for example, a laser, and the wide end 177 c of the thirddrain electrode 175 c and the expansion 126 of the common voltage line125 forming two terminals of the voltage-changing capacitor Cstd areshorted (the portion B) by, for example, using a laser.

Thus, as in the above-described exemplary embodiment, the first andsecond thin film transistors Qh and Q1 are separated from the data line171 such that they are not applied with the data voltage, and the drainelectrode 175 c of the third thin film transistor Qc is directlyconnected to the common voltage Vcom. The repairing method and theseveral characteristics of the liquid crystal display according to theexemplary embodiment shown in FIG. 8 to FIG. 10 may be applied to thepresent exemplary embodiment.

According to an exemplary embodiment, the source electrodes of the firstand second thin film transistors in the pixel that is defective in aliquid crystal display are disconnected from the data line and the twoterminals of the voltage-changing capacitor are shorted such that thefirst subpixel electrode or the first and second subpixel electrodes areapplied with the common voltage, thereby repairing the defective pixel.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A liquid crystal display comprising a plurality of data lines and aplurality of pixels arranged in a matrix, wherein the plurality ofpixels include a first pixel and a second pixel, and each of the firstpixel and the second pixel includes: a first subpixel electrode and asecond subpixel electrode; a first switching element including a firstdrain electrode connected to the first subpixel electrode and a firstsource electrode opposing the first drain electrode; a second switchingelement including a second drain electrode connected to the secondsubpixel electrode and a second source electrode opposing the seconddrain electrode; a third switching element including a third sourceelectrode connected to the second drain electrode and a third drainelectrode opposing the third source electrode; and a voltage-changingcapacitor including the third drain electrode and a common voltage linetransmitting a common voltage as its two terminals, wherein the firstsource electrode and the second source electrode of the first pixel areconnected to a data line of the plurality of data lines, the firstsource electrode and the second source electrode of the second pixel aredisconnected from any of the plurality of data lines, and the twoterminals of the voltage-changing capacitor of the second pixel areshorted to each other.
 2. The liquid crystal display of claim 1, furthercomprising a plurality of first gate lines, wherein one first gate lineis connected to the first switching element and the second switchingelement of the first pixel and one first gate line is connected to thefirst switching element and the second switching element of the secondpixel and a plurality of second gate lines, wherein one second gate lineis connected to the third switching element of the first pixel and onesecond gate line is connected to the third switching element of thesecond pixel.
 3. The liquid crystal display of claim 2, wherein thefirst subpixel electrode of the second pixel is electrically connectedto the first source electrode of the second pixel independently of agate signal of the first gate line.
 4. The liquid crystal display ofclaim 3, wherein the second subpixel electrode of the second pixel iselectrically connected to the second source electrode of the secondpixel independently of a gate signal of the first gate line.
 5. Theliquid crystal display of claim 4, wherein the second gate line isapplied with a gate-off voltage Voff when the first gate line is appliedwith a gate-on voltage Von, and the first gate line is applied with thegate-off voltage Voff when the second gate line is applied with thegate-on voltage Von.
 6. The liquid crystal display of claim 2, whereinthe second subpixel electrode of the second pixel is electricallyconnected to the second source electrode of the second pixelindependently of a gate signal of the first gate line.
 7. The liquidcrystal display of claim 6, wherein the second gate line is applied witha gate-off voltage Voff when the first gate line is applied with agate-on voltage Von, and the first gate line is applied with thegate-off voltage Voff when the second gate line is applied with thegate-on voltage Von.
 8. The liquid crystal display of claim 2, whereinthe second gate line is applied with a gate-off voltage Voff when thefirst gate line is applied with a gate-on voltage Von, and the firstgate line is applied with the gate-off voltage Voff when the second gateline is applied with the gate-on voltage Von.
 9. The liquid crystaldisplay of claim 8, wherein in the first pixel, the voltages of thefirst subpixel electrode and the second subpixel electrode are changedwhen the second gate line is applied with the gate-on voltage Von. 10.The liquid crystal display of claim 8, wherein in the second pixel, thecommon voltage is transmitted to the second subpixel electrode when thesecond gate line is applied with the gate-on voltage Von.
 11. The liquidcrystal display of claim 10, wherein in the second pixel, the firstsubpixel electrode is electrically connected to the second subpixelelectrode when the first gate line is applied with the gate-on voltageVon.
 12. The liquid crystal display of claim 2, wherein in the secondpixel, the second subpixel electrode is applied with the common voltagewhen the second gate line is applied with the gate-on voltage Von. 13.The liquid crystal display of claim 12, wherein in the second pixel, thefirst subpixel electrode is also applied with the common voltage whenthe second gate line is also applied with the gate-on voltage Von. 14.The liquid crystal display of claim 1, wherein the common voltage istransmitted to the second subpixel electrode in the second pixel. 15.The liquid crystal display of claim 14, wherein in the second pixel, thefirst subpixel electrode is electrically connected to the secondsubpixel electrode when the first gate line is applied with the gate-onvoltage Von.
 16. The liquid crystal display of claim 14, wherein thecommon voltage is also transmitted to the first subpixel electrode inthe second pixel.